Light emitting device

ABSTRACT

A light emitting device includes a package body, a light-transmissive cover, one or more semiconductor laser elements, a wavelength converting member, a wiring, electrically conductive layers, an opaque electrically insulating member, and electrodes. The light-transmissive cover is secured to the package body. The wavelength converting member is disposed above the light-transmissive cover in an optical path of the laser light emitted from the semiconductor laser element. The wiring is disposed on a light incidence surface-side of the wavelength converting member. The electrically conductive layers are electrically connected to the wiring and disposed on an upper surface of the light-transmissive cover. The electrically insulating member at least partially covers the electrically conductive layers and the light-transmissive cover. The electrodes are disposed on a surface of the package body at locations outward of the electrically insulating member in a plan view, and electrically connected to the electrically conductive layers.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

The present application claims priority under 35 U. S. C. § 119 toJapanese Patent Application No. 2018-059539, filed Mar. 27, 2018. Thecontents of Japanese Patent Application No. 2018-059539 are incorporatedherein by reference in their entirety.

BACKGROUND Technical Field

The present disclosure relates to a light emitting device.

Description of Related Art

There have been known light emitting devices employing one or moresemiconductor laser elements. In such light emitting devices, in orderto reduce leakage of laser light, a current path is provided by formingan electrically conducting film on a wavelength converting member whichis to be irradiated by laser light (for example, illustrated in JapaneseUnexamined Patent Publications No. 2015-60159 and No. 2016-122715). Thatis, when the current path formed on the wavelength converting member isdisconnected, it is determined that an abnormality, such as detachmentof the wavelength converting member from its predetermined position,occurrence of cracks, or the like has occurred, and the lasing isstopped.

SUMMARY OF THE INVENTION

However, even when cracks occur in the wavelength converting member, ifthe current path is maintained by, for example, adhesion of a water dropon the electrically conductive film or the like and provides anelectrical connection, the occurrence of the cracks may not be detected.Further, light emitting devices are expected to have simpler structureswhile being capable of detecting such abnormality. The presentdisclosure is devised in light of such circumstances, and it is hence anobject thereof to provide a light emitting device that can reliablydetect occurrence of abnormality that may cause leakage of laser light.

A light emitting device according to certain embodiments includes apackage body, a light-transmissive cover, one or more semiconductorlaser elements, a wavelength converting member, a wiring, electricallyconductive layers, an opaque electrically insulating member, andelectrodes. The light-transmissive cover is directly or indirectlysecured to the package body. The semiconductor laser element isconfigured to emit a laser light and disposed in a space enclosed by thepackage body and the light-transmissive cover. The wavelength convertingmember is disposed above the light-transmissive cover in an optical pathof the laser light emitted from the one or more semiconductor laserelements. The wiring is disposed on a light incidence surface-side ofthe wavelength converting member. The electrically conductive layers areelectrically connected to the wiring and disposed on an upper surface ofthe light-transmissive cover. The opaque electrically insulating membercovers at least parts of the electrically conductive layers and a partof the light-transmissive cover. The electrodes are disposed on asurface of the package body at locations outward of the electricallyinsulating member in a plan view, and electrically connected to theelectrically conductive layers.

In the light emitting device as described above, abnormality that maycause leakage of a laser light can be reliably detected and also areduction in the size of the light emitting device can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic perspective view illustrating a configuration ofa light emitting device according to one embodiment of the presentinvention.

FIG. 1B is a plan view of the light emitting device shown in FIG. 1A.

FIG. 1C is a schematic sectional view taken along line IC-IC′ of FIG.1B.

FIGS. 2A to 2D are schematic diagrams for illustrating forming of thewiring of the light emitting device shown in FIG. 1A.

FIG. 3A is a schematic top view of a light-transmissive cover of thelight emitting device shown in FIG. 1A.

FIG. 3B is a schematic bottom view of the light-transmissive cover ofthe light emitting device shown in FIG. 1A.

FIG. 4 is a schematic plan view showing a variational example of wiringsof the light emitting device shown in FIG. 1A.

FIG. 5 is a schematic plan view showing a variational example of thelight emitting device.

FIG. 6 is a functional block diagram of a driving device of the lightemitting device.

DETAILED DESCRIPTION OF EMBODIMENTS

Certain embodiments according to the present invention will be describedbelow with reference to the accompanying drawings. It is to be notedthat the light emitting device described below is intended forimplementing the technical concept of the present invention, and thepresent invention is not limited to those described below unlessotherwise specified. Note that, the size, positional relationship andthe like in the drawings may be exaggerated for the sake of clarity.

A light emitting device 10 according to one embodiment of the presentinvention includes, as shown in FIG. 1A to FIG. 1C, a package body 11and a light-transmissive cover 12, a semiconductor laser element 13, awavelength converting member 14, a wiring 15 disposed at alight-incident surface side of the wavelength converting member 14,electrically conductive layers 16 disposed on an upper surface of thelight-transmissive cover 12, an electrically insulating member 17covering the electrically conductive layers 16 and thelight-transmissive cover 12, and electrodes 18 a, 18 b disposed on anupper surface of the package body 11. In the present specification, asurface at a light-extracting side (an upper side in FIG. IC) isreferred to as an “upper surface” and a surface opposite to the uppersurface (a lower side in FIG. 1C) is referred to as a “lower surface”,in the light emitting device 10.

In the light emitting device 10 as describe above, abnormality that mayresult in leakage of laser light can be detected more reliably by usingthe wiring 15 and the electrically conductive layers 16. That is, thewiring 15 and the electrically conductive layers 16 are covered by thewavelength converting member 14 and the electrically insulating member17 such that the wiring 15 and the electrically conductive layers 16 arenot exposed to the outside. Accordingly, possibility of unintendedcurrent paths forming, such as short-circuits, due to adhesion of awater drop or the like on the wiring 15 can be reduced. Further, anopaque electrically insulating member 17 is disposed to cover theelectrically conductive layers 16 such that light from the semiconductorlaser element 13 can be blocked by the electrically insulating member17. Accordingly, the light-transmissive cover 12 substantially formedwith a light-transmissive material can be used as a member to enclosethe semiconductor laser element 13, which can realize further reductionin size of the light emitting device 10.

Package Body 11

The package body 11 is a member constituting a package to house thesemiconductor laser element 13. The package further includes alight-transmissive cover 12. The package body 11 defines a recess withan upward opening to house the semiconductor laser element 13. Thepackage body 11 preferably has at least one inner lateral wall part 11 bspaced apart from and surrounding the wavelength converting member 14.Accordingly, when a resin material is used for the electricallyinsulating member 17, the resin material can be stemmed or contained bythe inner lateral wall part 11 b, and thus the electrically insulatingmember 17 can be easily disposed. The inner lateral wall part 11 bdefines a part of the recess. The package body 11 preferably has aprotruding surface 11 a protruding inward from the inner lateral wallpart 11 b in a plan view, to secure the light-transmissive cover 12.Accordingly, the light-transmissive member 12 can be stably secured. Theprotruding surface 11 a may be a part of a first step located below theinner lateral wall part 11 b, defining another part of the recess. Theprotruding surface 11 a is, for example, a surface substantially inparallel to a lowermost surface of the package body 11. The innerlateral wall part 11 b may be in contact with the protruding surface 11a, but as shown in FIG. 1C, two or more steps respectively definingparts of the recess may be arranged and a second step may be providedbetween the inner lateral wall part 11 b and the protruding surface 11a. A metal layer to be connected with the wire 23, which will bedescribed below, can be disposed on the second step.

The package body 11 may be mainly made of ceramics such as aluminumoxide, aluminum nitride, silicon nitride, or silicon carbide, or a metalsuch as Cu. As shown in FIG. 1C, when electrically conductive memberssuch as metal layers are disposed inside of the package body 11,ceramics is preferably used for the package body 11 to avoid occurrenceof short-circuit between the electrically conductive members. Thepackage body 11 has, for example, as shown in FIG. 1B, a quadrangularshape in a plan view.

In this case, the package body 11 preferably has an upper surfaceadjacent to and surrounding the recess in four sides, in which regionsof the upper surface in two of the sides have greater areas than that ofother regions of the upper surface in the other two of the sides, toplace the electrodes 18 a, 18 b, 21 a, and 21 b to be described below.

Power-supplying Electrodes 21 a, 21 b

The package body 11 includes power-supplying electrodes 21 a and 21 b tosupply power to the semiconductor laser element 13. The power-supplyingelectrodes 21 a and 21 b are positive and negative electrodes,respectively. The power-supplying electrodes 21 a and 21 b are disposedon a surface, for example, on the upper surface, of the package body 11.The power-supplying electrodes 21 a and 21 b to be electricallyconnected to the outside are disposed on a surface other than a lowersurface of the package body 11, such that an entire portion of the lowersurface of the package body 11 can be used for mounting to other memberssuch as a heat sink. Accordingly, dissipation of heat generated from thelight emitting device 10 to the heat sink or the like can befacilitated. The light emitting device 10 can be combined with, forexample, a heat dissipation plate on which the lower surface of thelight emitting device 10 is secured, and connectors respectivelyconnected to the electrodes 18 a and 18 b, and the power-supplyingelectrodes 21 a and 21 b, to structure a light emitting module. In thelight emitting module, a height of a light emitting point can be set,for example, in a height from a lower surface of the heat dissipationplate to an upper surface of the wavelength converting member 14 (i.e.,a fluorescent material containing part 14 a) of the light emittingdevice 10. The height of the light emitting point can be determined bythe respective thicknesses of the heat dissipation plate and the lightemitting device 10. When the thicknesses of the light emitting devices10 tend to deviate, such as when a stacked-layer structure of ceramicsis used for the package body 11 of the light emitting device 10, theactual thickness of the light emitting device 10 can be measured and theheat dissipation plate of appropriate thickness can be used incombination. With this arrangement, deviation in the heights of thelight emitting points of the light emitting modules can be reduced.Alternatively, dividing the thicknesses of the light emitting devices 10and the heat dissipation plates into several ranks, and an appropriatecombination may be determined for respective ranks. The heat dissipatingplate is thermally connected to a heat sink, for example. Thepower-supplying electrodes 21 a and 21 b are disposed outward of theelectrically insulating member 17. That is, the power-supplyingelectrodes 21 a and 21 b are exposed from the electrically insulatingmember 17. As shown in FIG. 1A, the power-supplying electrode 21 a isdisposed closer to the electrode 18 a and the power supplying electrode21 b is disposed closer to the electrode 18 b. Accordingly, terminals ofthe connectors to supply electricity to the electrodes can be easilydisposed. The power-supplying electrodes 21 a and 21 b are electricallyconnected to the electrically conductive layer disposed on the bottomsurface of the recess of the package body 11 via the electricallyconductive members internally disposed of the package body 11. Thepower-supplying electrodes 21 a and 21 b can be made of an electricallyconductive material such as Au, Sn, Ag, Cu, Ni, Rh, Pd, Al, W, Pt, orTi, respectively.

Light-Transmissive Cover 12

The light-transmissive cover 12 is directly or indirectly fixed to thepackage body 11 to enclose the semiconductor laser element 13 and othercomponents in the recess of the package body 11. By hermetically sealingthe semiconductor laser element 13 with such fixation, adhesion of dustsuch as an organic material to the semiconductor laser element 13 can beprevented or reduced. The light-transmissive cover 12 haslight-transmissive property, which allows the laser light emitted fromthe semiconductor laser element 13 to pass through. Thelight-transmissive cover 12 having a transmittance to the laser lightof, for example, 70% or greater, 80% or greater, or 90% or greater, canbe employed. For this purpose, the light-transmissive cover 12 can bemade of glass, sapphire, or the like. Of those, the light-transmissivecover 12 is preferably made of sapphire, which has a high thermalconductivity. Accordingly, the heat of the wavelength converting member14 can be dissipated efficiently to the light-transmissive cover 12.When sapphire is used for the light-transmissive cover 12, the thicknessmay be in a range of 0.1 mm to 5 mm, preferably in a range of 0.3 mm to1 mm. Accordingly, the mechanical strength of the light-transmissivecover 12 can be securely obtained, and heat dissipation performance canalso be improved.

As described above, the light-transmissive cover 12 can be fixed to theprotruding surface 11 a in the recess of the package body 11. Thelight-transmissive cover 12 can be directly fixed to the package body11, by using room-temperature bonding such as surface activated bonding,atomic diffusion bonding, or the like. The light-transmissive cover 12can be indirectly fixed to the package body 11, for example, as shown inFIG. 1C, via the metal bonding layer 27. The metal bonding layer 27 canbe located between the metal layer 25 disposed on a surface of thelight-transmissive cover 12 and the metal layer 25 disposed on theprotruding surface 11 a of the package body 11.

Metal Layer 25

The metal layer 25 can be disposed, for example as shown in a plan viewof FIG. 3B, on a peripheral part of the lower surface 12L of thelight-transmissive cover 12. In addition, as shown in FIG. 1C, the metallayer 25 may be disposed on the protruding surface 11 a of the packagebody 11. FIG. 3B is a bottom view of the lower surface of thelight-transmissive cover 12, in which the light-transmissive part thatis not covered by the metal layer 25 is indicated by hatching for theease of distinguishing the components. The metal layer 25 can be made ofa metal material containing at least one selected from a groupconsisting of Au, Sn, Ag, Cu, Ni, Rh, Pd, Al, W, Pt, and Ti. Examples ofthe metal material include a layered film of Ti/Pt/Au, or a layered filmof W/Ni/Au. The metal layer 25 can have a thickness in a range of, forexample, 0.1 μm to 5 μm.

Metal Bonding Layer 27

Examples of the material of the metal bonding layer 27 include solderssuch as Sn—Bi-based solder, Sn—Cu-based solder, Sn—Ag-based solder, andAu—Sn-based solder; alloys having Au and Sn as main components, alloyshaving Au and Si as main components; eutectic alloys having Au and Ge asmain components; low-melting-point metal brazing materials; and adhesivematerials of combination of those. The semiconductor laser element 13can be sealed by a small number of components, as described above, byusing the package body 11 and the light-transmissive cover 12, or byusing the package body 11 and the light-transmissive cover 12respectively having a metal layer or the like on the surface thereof.Accordingly, a reduction in the size of the light emitting device can berealized.

Semiconductor Laser Element 13

The semiconductor laser element 13 is disposed within a space enclosedby the package body 11 and the light-transmissive cover 12. Thesemiconductor laser element 13 may be directly disposed on the bottomsurface defining the recess of the package body 11, but can be disposedon a sub-mount 19 as shown in FIG. 1C. The semiconductor laser element13 can be mounted such that laser light emitted from the semiconductorlaser element 13 propagates in a direction substantially parallel to thebottom surface defining the recess of the package body 11.

The shorter the wavelength of laser light emitted from the semiconductorlaser element 13, the higher its energy, which increase demand fordetecting leakage of the laser light. The semiconductor laser element 13can be configured to emit a short-wavelength laser light such as bluelight. The semiconductor laser element 13 can be made of nitride-basedsemiconductor.

The sub-mount 19 may be made of a material whose main component is SiC,AlN, or the like. The semiconductor laser element 13 can be mounted onthe sub-mount 19, for example, by using an AuSn eutectic solder or thelike.

As shown in FIG. IC, the semiconductor laser element 13 is preferablydisposed facing the light-reflecting member 20 that is disposed withinthe space enclosed by the package body 11 and the light-transmissivecover 12. With this arrangement, laser light emitted from thesemiconductor laser element 13 is irradiated on the light-reflectingmember 20, and reflected toward the light-transmissive cover 12 fixed tothe upper surface side of the package base 11, and can be incident onthe wavelength converting member 14 to be described below. For example,the light-reflecting member 20 may be made of glass or Si or the like,having a shape such as triangular prism shape, a quadrangular truncatedcone shape, or the like, having a main part that has a surface inclinedwith respect to a lower surface thereof and a light reflecting filmdisposed on the inclined surface. The angle of the inclined surface tothe lower surface of the main part is preferably about 45 degrees inorder to guide the laser light in a direction perpendicular to the lowersurface of the package base 11. For the light-reflecting film, a singlelayer or multilayer dielectric film, a single layer or multilayer metalfilm, or the like, can be employed.

Wavelength Converting Member 14

The wavelength converting member 14 is configured to convert laser lightemitted from the semiconductor laser element 13 to a light of adifferent wavelength, and has a light-incident surface 14I facing thelight-transmissive cover 12 and a light-emitting surface 14E at anopposite side of the light-incident surface 14I. The wavelengthconverting member 14 preferably has a fluorescent material containingpart 14 a arranged in an optical path of the laser light, and alight-reflecting part 14 b surrounding the fluorescent materialcontaining part 14 a. As described above, with the light-reflecting part14 b arranged between the fluorescent material containing part 14 a andthe electrically insulating member 17, even when the electricallyinsulating member 17 is also a light-absorption member, a decrease inthe optical output of the light emitting device 10 can be avoided orreduced. The fluorescent material containing part 14 a of the wavelengthconverting member 14 is disposed above the light-transmissive cover 12and in the optical path of the laser light emitted from thesemiconductor laser element 13. The light-reflecting part 14 b can bedisposed to cover lateral surface(s) of the fluorescent materialcontaining part 14 a. The term “lateral surface(s) of the fluorescentmaterial containing part 14 a” refers to surface(s) connecting the lightincidence surface and the light emitting surface of the fluorescentmaterial containing part 14 a.

The fluorescent material containing part 14 a and the light-reflectingpart 14 b of the wavelength converting member 14 are preferably made ofan inorganic material so they are not easily degraded by irradiation ofthe laser light. The fluorescent material containing part 14 a made ofan inorganic material may be ceramics or glass containing a fluorescentmaterial or made of a single crystal of a fluorescent material, whichcan convert the laser light into light of a different wavelength.Moreover, the wavelength converting member 14 is preferably made of amaterial that has a high melting point in a range of 1,300° C. to 2,500°C. With the use of such material, good light-resisting properties andgood heat resisting properties can be obtained. Thus, occurrence ofdegradation can be reduced even when irradiated with high-density lightsuch as a laser light.

When ceramics is used for the fluorescent material containing member 14a, for example, a sintered material of a fluorescent material and alight-transmissive material such as aluminum oxide (Al₂O₃, melting pointin a range of about 1,900° C. to about 2,100° C.) can be used. In thiscase, the content of the fluorescent material can be in a range of 0.05volume % to 50 volume %, or in a range of 10 volume % to 40 volume %,with respect to a total volume of the ceramics. Alternatively, ceramicssubstantially made of only the fluorescent material, obtained bysintering powder of fluorescent material without using such alight-transmissive material, can also be used as the fluorescentmaterial containing part 14 a.

Examples of the fluorescent materials include yttrium aluminum garnet(YAG) activated with cerium, lutetium aluminum garnet (LAG) activatedwith cerium, nitrogen-containing calcium aluminosilicate(CaO—Al₂O₃—SiO₂) activated with europium and/or chromium, silicate ((Sr,Ba)₂SiO₄) activated with europium, α-sialon-based fluorescent material,and β-sialon-based fluorescent material. Of those, a YAG fluorescentmaterial that has good heat-resisting properties is preferably used.

The wavelength converting member 14 includes the light-reflecting part14 b formed with a through hole penetrating along its thicknessdirection, and a fluorescent material containing part 14 a fitted in thethrough hole. The shape defining the through-hole, that is, the shape ofthe fluorescent material containing part 14 a can be corresponding tothe shape of the wavelength converting member 14. Examples thereofinclude a quadrangular prism-shape, a truncated cone shape, aquadrangular truncated cone shape, or a combination of those shapes,with a shape in a plan view of, for example, a polygonal shape such as atriangular shape or a quadrangular shape, a circular shape, or anelliptic shape.

The wavelength converting member 14 preferably has a thickness of 0.2 mmor greater, in view of mechanical strength, and 2.0 mm or less, in viewof minimizing a rise in cost and height of the light emitting device.

The light-reflecting part 14 b is preferably made of a material that canreflect the laser light and fluorescent light emitted from thefluorescent material at a high reflectance, and also has a high thermalconductivity to release heat from the fluorescent material containingpart 14 a retained in the through-hole. Examples of the material havinga high reflectance and high thermal conductivity includelight-reflecting ceramics, a metal, and a composite of ceramics andmetal. The light-reflecting part 14 b is preferably made oflight-reflecting ceramics with which a high reflectance can be easilyobtained. For such light-reflecting ceramics, alumina (Al₂O₃) ceramicscan be used. Forming the light-reflecting part 14 b with a materialhaving a high reflectance allows for extraction of light within thewavelength converting member 14 mainly from the upper surface of thefluorescent material containing part 14 a, and thus higher luminance canbe achieved. Moreover, laser light irradiated to members other than thefluorescent material containing part 14 a can be prevented from leakingto the outside. Further, with the arrangement described above, lightfrom the fluorescent material containing part 14 a can be substantiallyprevented from reaching the electrically insulating member 17.Accordingly, even when the electrically insulating member 17 is formedwith a light-absorption material, the optical output of the lightemitting device can be maintained.

The light-reflecting part 14 b may have a surface coplanar with thelight-emitting surface 14E of the fluorescent material containing part14 a (i.e. an uppermost surface of the fluorescent material containingpart 14 a), or a portion or all of the light-emitting surface 14E of thefluorescent material containing part 14 a may be arranged protrudingfrom the upper surface of the light-reflecting part 14 b. The uppermostsurface of the light-emitting surface 14E (in particular, the uppermostsurface of the fluorescent material containing part 14 a) of thewavelength converting member 14 is preferably arranged protruding fromthe upper surface of the package body 11. With this arrangement, lightextracted from the wavelength converting member 14 in an upwarddirection being blocked by the package body 11 can be reduced, and thus,the light extraction efficiency of the light emitting device 10 can beincreased.

The wavelength converting member 14 can be formed such that, forexample, the fluorescent material containing part 14 a made of a moldedbody (e.g., sintered body) and powder or particle form of a material ofthe light-reflecting part 14 b are integrally molded, or powder orparticle form of a material of the fluorescent material containing part14 a and the light-reflecting part 14 b made of a molded body areintegrally molded, and the integrally molded part is sintered. Forsintering, for example, a spark plasma sintering method (SPS method), ahot-pressing method (HP method), or the like, can be used. When aluminais used as a powder form of the light-reflecting part 14 b, thesintering temperature in a range of 1,200° C. to 1,800° C. can be used.

The wavelength converting member 14 can be fixed to thelight-transmissive cover 12 via the wiring 15 and the electricallyconductive layer 16, to be described below. Either an electricallyinsulating material or an electrically conductive material can be usedfor fixing the wavelength converting member 14. Fixing the wavelengthconverting member 14 to the light-transmissive cover 12 can beperformed, as shown in FIG. 1C, FIG. 2D, and FIG. 3A and as describedbelow, by disposing a metal layer 22 and an electrically conductivebonding layer 26 a and the like, respectively between the wiring 15 andthe electrically conductive layer 16. Alternatively, for example, normaltemperature bonding as described above may be performed, without usingthe electrically conductive bonding layer 26 a.

Wiring 15

The wiring 15 is disposed at the light incidence surface 14I side of thewavelength converting member 14, where the laser light emitted from thesemiconductor laser element 13 is incident. The wiring 15 is made of anelectrically conducting material. When at least a portion of the wiring15 is disposed on the fluorescent material containing part 14 a of thewavelength converting member 14, the wiring 15 is preferably formed witha light-transmissive electrically conductive film. Accordingly,absorption of light by the wiring 15 can be reduced. For thelight-transmissive electrically conductive film, indium tin oxide (ITO)having a high reflectance to visible light can be used. In a region ofthe wiring 15 to be electrically connected to the electricallyconductive layer 16, which will be described below, in order to increaseadhesion to the electrically conductive layer 16, a layered film havingan Au layer as an uppermost surface, such as a Ti/Pt/Au layer, isdisposed on the ITO layer such that the layered film serves as anuppermost surface of the wiring 15.

The wiring 15 may be disposed on a lower surface of the light-reflectingpart 14 b or a lower surface of the fluorescent material containing part14 a of the wavelength converting member 14, or alternatively, thewiring 15 may be disposed on the light-reflecting part 14 b and extendedonto the fluorescent material containing part 14 a. The wiring 15 may bedisposed in a linear shape with a width in a range of about 5 μm toabout 50 μm. The wiring 15 may be disposed continuously between twoopposite ends of the wavelength converting member 14. Alight-transmissive film may be provided between the wiring 15 and thewavelength converting member 14.

The length, the width, the thickness, the pitch, or the like of thewiring 15 can be appropriately determined according to the dimensions ofthe wavelength converting member 14, the dimensions of the fluorescentmaterial containing part 14 a, or the like. The wiring 15 may have aconstant width and thickness, or may have partially different width andthickness. The wiring 15 may be disposed in a shape having either aregularly-formed or randomly-formed bendings or curves.

More specifically, as shown in FIG. 4, the wiring 15A may be disposedonly on the light-reflecting part 14 b at the light incidence surface14I side of the wavelength converting member 14. The wiring 15A maycompletely surround the fluorescent material containing part 14 a in aplan view, as shown in FIG. 4, or may surround only a portion of thefluorescent material containing part 14 a in a plan view.

The wiring 15 can be disposed, for example as shown in FIG. 2A, byproviding the wavelength converting member 14, and depositing a film ofthe material for the wiring 15 by using a sputtering method, chemicalvapor deposition method, atomic layer deposition method, or the like, onthe light incidence surface 14I of the wavelength converting member 14,as shown in FIG. 2B.

Insulating Film 24

The wiring 15 is preferably covered by the electrically insulating layer24. With the electrically insulating film 24, the metal film 22 a to bedescribed below and the wiring 15 can be insulated from each other,allowing for greater planar dimension for the metal film 22 a. Theelectrically insulating film 24 can be disposed, for example as shown inFIG. 2C, on substantially an entire surface of the light incidencesurface 14I of the wavelength converting member 14, except for theopenings 24 a that expose portions of the wiring 15 at the both ends ofthe wiring 15. The electrically insulating film 24 is preferably alight-transmissive film when disposed in the optical path of the laserlight. With this arrangement, absorption of the laser light by theinsulating layer 24 can be reduced. Examples of the light-transmissivefilm include a film containing an oxide of silicon such as SiO₂. Thethickness of the electrically insulating film 24 may be, for example, ina range of 1 μm to 15 μm.

Metal Layer 22

As shown in FIG. 2D, in order to facilitate electrical connection to theelectrically conductive layers 16 to be described below, metal films 22are preferably formed under the electrically insulating films 24 (i.e.,in a direction away from the wavelength converting member 14), in aregion under the light incidence surface 14I of the wavelengthconverting member 14. The metal films 22 can be electrically connectedto a respective part of the wiring 15 through the through-openings 24 adefined in the electrically insulating film 24 near the opposite ends ofthe wiring 15. The planar area of the metal film 22 is greater than theplanar area defining the opening 24 a. In addition, at the lightincidence surface 14I of the wavelength converting member 14, the metalfilms 22 a may be disposed to surround the wiring 15 disposed on thefluorescent material containing part 14 a. The metal films 22 a can beformed at the same time with the metal films 22 used to connect to theelectrically conductive layer 16. The metal films 22 a can be used as apart of the surrounding member 26 to be described below.

Electrically Conductive Layers 16

The electrically conductive layers 16 are disposed on the upper surfaceof the light-transmissive cover 12, and are electrically connected torespective parts of the wiring 15. In a plan view, the electricallyconductive layer 16 can be disposed such that at least a part of theelectrically conductive layer 16 is overlapped with the wiring 15. Forexample, as shown in FIG. 3A, the electrically conductive layers 16 arepreferably overlapped with respective end parts of the wiring 15. Theelectrically conductive layers 16 preferably have locations anddimensions so as not to overlap with parts of the fluorescent materialcontaining part 14 a. With this arrangement, light incident on thefluorescent material containing part 14 a can be prevented from beingblocked or intervened by the electrically conductive layers 16. FIG. 3Ais a schematic top view, but in order to facilitate recognition of themembers, the members are shown by hatching. The electrically conductivelayers 16 can be made of an electrically conducting material. Examplesof the material of the electrically conductive layers 16 include asingle film or a layered film made of one or more metals such as Au, Sn,Ag, Cu, Ni, Rh, Pd, Al, W, Pt, and Ti or one or more alloys of those.For example, a layered film of Ti/Pt/Au/Au—Sn alloy may be used. Thethickness of the electrically conductive layers 16 can be, for example,in a range of 0.2 μm to 10 μm. Also, as shown in FIG. 3A, anelectrically conductive layer 16 a may be disposed on the upper surface12U of the light-transmissive cover 12 such that the electricallyconductive layer 16 a surrounds the wiring 15 disposed on thefluorescent material containing part 14 a. The electrically conductivelayer 16 a can be disposed simultaneously with the electricallyconductive layers 16 that are provided to be connected to the wiring 15.The electrically conductive layer 16 a can be used as a part of asurrounding member 26 to be described below.

Electrically Insulating Member 17

The electrically insulating member 17 is disposed to cover theelectrically conductive layers 16 and the light-transmissive cover 12.The electrically insulating member 17 does not necessarily have to coverthe entire surfaces of the electrically conductive layers 16 and thelight-transmissive cover 12. It is sufficient for the electricallyinsulating member 17 to cover the upper surfaces and lateral surfaces ofthe electrically conductive layers 16 and the upper surface of thelight-transmissive cover 12. As described above, when the package body11 has an inner lateral wall part 11 b spaced apart from and surroundingthe wavelength converting member 14, the electrically insulating member17 can be disposed to fill between the wavelength converting member 14and the inner lateral wall part 11 b. In other words, the inner lateralwall part 11 b can be used to block the flow of the material of theelectrically insulating member 17. Further, if a gap is present betweenthe light-transmissive cover 12 and the package body 11, it is morepreferable that the electrically insulating member 17 is also disposedto fill the gap. In other words, it is more preferable that the lateralsurfaces of the light-transmissive cover 12 are also covered by theelectrically insulating member 17. As described above, with theelectrically insulating member 17 filled between the light-transmissivecover 12 and/or the wavelength converting member 14 or the like, and thepackage body 11, heat dissipation performance can be improved comparedto the case in which such a gap is filled with air. This is thought tobe the reason why dissipation of heat from the wavelength convertingmember 14 is improved. The electrically insulating member 17 ispreferably disposed to completely cover the wires 23, in other words, itis preferable that the wires 23 are not exposed from the electricallyinsulating member 17. Accordingly, the wires 23 can be protected by theelectrically insulating member 17, and also forming of electricalconnection caused by adhesion of water drop or the like onto the wires23 can be prevented. For a similar reason, as shown in FIG. 1C, theelectrically conductive layers on the surfaces of the package body 11 towhich the wires 23 are connected, are also preferably covered by theelectrically insulating member 17.

The electrically insulating member 17 is preferably made of an opaquematerial, and more preferably, the electrically insulating member 17also serves as a light-absorption member. With the use of theelectrically insulating member 17 that is also a light-absorptionmember, light from the semiconductor laser element 13 is thought to bereliably blocked compared to the case in which the electricallyinsulating member 17 is a light-reflecting member. The electricallyinsulating member 17 is preferably made of a resin material, which canfacilitate disposing the electrically insulating member 17 into the gapor the like between the light-transmissive cover 12 and the package body11. In order to make the electrically insulating member 17 opaque and/orlight-absorbing, a light diffusing material and/or a light-absorbingfiller material can be contained in the resin. Examples of the resininclude an epoxy resin, a silicone resin, an acrylate resin, a urethaneresin, a phenol resin, and a BT resin. Examples of light-absorptionfiller include a dark pigment such as carbon black. With the use of thelight-absorbing electrically insulating member 17 as described above,leaking light such as leaking laser light can be reliably blockedcompared to the use of a light-reflecting electrically insulating member17. Note that in FIG. 1C, the electrically insulating member 17 isdisposed to a middle of the lateral surfaces of the wavelengthconverting member 14, but if a resin is used for the electricallyinsulating member 17, the electrically insulating member 17 may risealong the lateral surfaces of the wavelength converting member 14 to theupper edge of the lateral surfaces by surface tension.

Electrodes 18 a, 18 b

The electrodes 18 a and 18 b are disposed on a surface, for example, theupper surface, of the package body 11. The electrodes 18 a and 18 b aredisposed outward of the electrically insulating member 17. That is, theelectrodes 18 a and 18 b are exposed from the electrically insulatingmember 17. The electrodes 18 a and 18 b are electrically connected tothe respective electrically conductive layers 16 such that electricpower can be applied on the wiring 15 via the electrically conductivelayers 16. Accordingly, change in the value of electric voltage in thewiring 15 described above can be detected, which can allow detection ofdamage of wavelength converting member 14, in particular, damage of thefluorescent material containing part 14 a. In the present specification,the term “damage” as used above refers to crack(s), deviation in theposition, or the like, for example. In order to apply electric voltageto the wiring 15, at least two electrodes of a first electrode and asecond electrode are disposed as the electrodes 18 a and 18 b. Theelectrodes 18 a and 18 b that are the first electrode and the secondelectrode are, as shown in FIG. 1B, preferably disposed on oppositesides with respect to the wavelength converting member 14 on the packagebase body 11, in a plan view. With the arrangement as described above, alarge distance can be provided between the electrode 18 a and theelectrode 18 b. Accordingly, occurrence of short-circuit between theelectrodes due to water drop(s) or the like can be efficiently reducedor prevented.

The electrodes 18 a and 18 b are respectively electrically connected tothe respective electrically conductive layers 16. As shown in FIG. 1C,the electrically conductive layers 16 are electrically connected to themetal layers disposed on the package body 11 via the wires 23, and themetal layers can be electrically connected to the electrodes 18 a and 18b via the electrically conductive members internally disposed of thepackage body 11, respectively. The electrodes 18 a and 18 b can be madeof an electrically conducting material such as Au, Sn, Ag, Cu, Ni, Rh,Pd, Al, W, Pt, or/and Ti.

It is preferable that on the surface of the package body 11, one of theelectrodes 18 a and 18 b and one of the power supplying electrodes 21 aand 21 b are closely disposed, and the other one of the electrodes 18 aand 18 b and the other one of the power supplying electrodes 21 a and 21b are closely disposed, respectively. This arrangement can facilitatedesigning of the terminals of the module to which the light emittingdevice 10 is to be incorporated. For example, as shown in FIG. 1B, whenthe package body 11 has a substantially quadrangular shape in a planview, the electrode 18 a and the power-supplying electrode 21 a can bedisposed along one side, and the other electrode 18 b and the otherpower-supplying electrode 21 b can be disposed along an opposite side ofthe one side.

As shown in FIG. 5, at least one of the electrodes 18 a, 18 b, thepower-supplying electrodes 21 a, 21 b (for example, the electrode 18 ain FIG. 5) may have smaller planar dimensions than that of otherelectrodes. Such an arrangement allows for determining the orientationof the light emitting device 10. For example, the power supplyingelectrode at the side with smaller electrode can be determined as acathode. The exposed surface of the package body 11 obtained by formingcertain electrode (s) with smaller planar dimensions can be used forapplying a pattern such as a production serial number. Examples of sucha pattern include a two-dimensional code. The electrode having smallerplanar dimensions is preferably an electrode other than the powersupplying electrode 21 a or 21 b. This is because the power supplyingelectrodes 21 a and 21 b supply electric power to the semiconductorlaser element 13 and tend to be loaded with larger electric current thanother electrode(s).

Surrounding Member 26

It is preferable that the emitting device 10 further includes asurrounding member 26. The surrounding member 26 is, as shown in FIG.1C, disposed on the lower surface of the wavelength converting member 14and/or the upper surface of the light-transmissive cover 12, and asshown in FIG. 3A, encircles the region of the wavelength convertingmember 14 to which the laser light is to be incident. With thesurrounding member 26, the electrically insulating member 17 can beprevented from entering the optical path of the laser light. Inparticular, when a resin is used for the electrically insulating member17, the resin easily enters gaps, and thus, it is preferable to providethe surrounding member 26. The surrounding member 26 is, for example,formed with an electrically conductive layer 16 a, a metal layer 22 a,and a bonding material 26 c. The surrounding member 26 is preferablydisposed inward of the electrically conductive bonding layer 26 a, inother words, between the electrically conductive bonding layer 26 a andthe light incident region of the wavelength converting member 14 onwhich the laser light is incident. Such an arrangement is preferablebecause as shown in FIG. 1C, the wires 23 are connected to theelectrically conductive layers 16 that are connected to the electricallyconductive bonding layers 26 a. The surrounding member 26 can bedisposed to completely surround the light-incident region. Thesurrounding member 26 can be disposed, for example, to demarcate theregion that is directly under the fluorescent material containing part14 a, or to demarcate a region smaller or larger than the region that isdirectly under the fluorescent material containing part 14 a. Inparticular, the surrounding member 26 is preferably disposed todemarcate a region slightly larger than the region that is directlyunder the fluorescent material containing part 14 a. This arrangementcan prevent light incident on the fluorescent material containing part14 a from being blocked or intervened by the surrounding member 26. Whenthe wiring 15A is disposed only on the light-reflecting part 14 b at thelight incidence surface 14I side of the wavelength converting member 14,to surround at least a portion of the fluorescent material containingpart 14 a in a plan view, the surrounding member 26 can also be disposedto surround the portion of the wiring 15A that surrounds at least aportion of the fluorescent material containing part 14 a, in the planview.

The surrounding member 26 can be made of either an electricallyinsulating material or an electrically conductive material, or acomposite material of those. The electrically insulating material can bemade of a similar material used for the electrically insulating member17, the package body 11, the light-reflecting part 14 b, or theelectrically insulating film 24. The electrically conducting materialcan be made of a similar material used for the wiring 15, electricallyconductive layers 16, the metal film 22, the metal layer 25, or themetal bonding layer 27. In particular, the surrounding member 26 ispreferably made of a member similar to those used to establishelectrical connection between the wiring 15 and the electricallyconductive layers 16, because of the ease of forming. For example, thesurrounding member 26 can be formed with a metal layer 22 a as shown inFIG. 1C and FIG. 2D, an electrically conductive layer 16 a as shown inFIG. 1C and FIG. 3A and a bonding material 26 c disposed between themetal film 22 a and the electrically conductive layer 16 a as shown inFIG. 1C and FIG. 3A. The bonding material 26 c can be a material similarto the material of the metal bonding layer 27 as described above. Whenthe surrounding member 26 is formed with such members as describedabove, a sum of the thicknesses of those members preferably correspondsto a height that can close the gap between the wavelength convertingmember 14 and the light-transmissive cover 12. Accordingly, theelectrically insulating member 17 can be prevented from entering theoptical path of the laser light. It is preferable that the surroundingmember 26 is disposed with a height corresponding to the height that canclose the gaps between the wavelength converting member 14 and thelight-transmissive cover 12, even when the enclosing member 26 is formedwith a material or materials other than that described above.

Detection Circuit

The detection device 10 can be further equipped with a detection circuitconfigured to detect a change in the resistance values caused by damageof the wiring 15. The detection circuit can be connected to the wiring15 and a power supply circuit for the semiconductor laser element 13.With such a detection circuit, damage of the wavelength convertingmember 14 can be detected as a change in the resistance values caused bydamage of the wiring 15. Accordingly, at the time of detecting a changein the resistance value of the wiring 15, occurrence of damage to thewavelength converting member 14 and the light-reflecting part 14 b canbe determined, and the operation of the semiconductor laser element 13is stopped. Accordingly, leakage of the laser light can be prevented.

An example of a functional block diagram of the driving device of thelight emitting device is illustrated in FIG. 6. In FIG. 6, a destructiondetecting circuit is used as the detection circuit, and the wiring 15disposed on the wavelength converting member 14 is connected to thedestruction detecting circuit. Upon detecting damage of the wiring 15,the destruction detecting circuit transmits a cut-off signal, and thesemiconductor laser element driving circuit stops the operation of thesemiconductor laser element upon receiving the cut-off signal.

It is to be understood that although the present invention has beendescribed with regard to preferred embodiments thereof, various otherembodiments and variants may occur to those skilled in the art, whichare within the scope and spirit of the invention, and such otherembodiments and variants are intended to be covered by the followingclaims.

What is claimed is:
 1. A light emitting device comprising: a packagebody; a light-transmissive cover directly or indirectly secured to thepackage body, the light-transmissive cover being substantially made of alight-transmissive material; one or more semiconductor laser elementsconfigured to emit a laser light and disposed in a space enclosed by thepackage body and the light-transmissive cover; a wavelength convertingmember disposed above the light-transmissive cover in an optical path ofthe laser light emitted from the one or more semiconductor laserelements, an outermost edge of the wavelength converting member beingdisposed inwardly of an outermost edge of the light-transmissive coverin a plan view; a wiring disposed on a light incidence surface-side ofthe wavelength converting member; electrically conductive layerselectrically connected to the wiring and disposed on an upper surface ofthe light-transmissive cover; an opaque electrically insulating membercovering at least parts of the electrically conductive layers and a partof the upper surface of the light-transmissive cover; and electrodesdisposed on a surface of the package body at locations outward of theelectrically insulating member in the plan view, and electricallyconnected to the electrically conductive layers.
 2. The light emittingdevice according to claim 1, wherein the electrically insulating memberis a light-absorption member.
 3. The light emitting device, according toclaim 1, wherein the wavelength converting member includes a fluorescentmaterial containing part disposed in the optical path of the laser lightemitted from the one or more semiconductor laser elements, and alight-reflecting part surrounding a lateral periphery of the fluorescentmaterial containing part in the plan view.
 4. The light emitting deviceaccording to claim 3, wherein the wiring is disposed only on thelight-reflecting part at the light incidence surface-side of thewavelength converting member.
 5. The light emitting device according toclaim 3, wherein a portion or all of a light-emitting surface of thefluorescent material containing part protrudes from an upper surface ofthe light-reflecting part.
 6. The light emitting device according toclaim 1, wherein the electrodes include a first electrode and a secondelectrode disposed at opposite sides with respect to the wavelengthconverting member in the plan view.
 7. The light emitting deviceaccording to claim 1, wherein the package body includes power supplyingelectrodes disposed on the upper surface of the package body atlocations outward of the electrically insulating member in the plan viewto supply electric power to the one or more semiconductor laserelements.
 8. The light emitting device according to claim 7, wherein theelectrodes include a first electrode and a second electrode disposed atopposite sides with respect to the wavelength converting member in theplan view, the power supplying electrodes include a first powersupplying electrode and a second power supplying electrode disposed atopposite sides with respect to the wavelength converting member in theplan view, and at least one of the first electrode, the secondelectrode, the first power supplying electrode and the second powersupplying electrode has a smaller planar dimension than that of otherelectrodes.
 9. The light emitting device according to claim 7, whereinthe electrodes include a first electrode and a second electrode disposedat opposite sides with respect to the wavelength converting member inthe plan view, the power supplying electrodes include a first powersupplying electrode and a second power supplying electrode disposed atopposite sides with respect to the wavelength converting member in theplan view, and one of the first electrode and the second electrode andone of the first power supplying electrode and the second powersupplying electrode are disposed adjacent to each other, and the otherone of the first electrode and the second electrode and the other one ofthe first power supplying electrode and the second power supplyingelectrode are disposed adjacent to each other.
 10. The light emittingdevice according to claim 1, wherein the package body includes at leastone inner lateral wall part spaced apart from and surrounding thewavelength converting member, and the electrically insulating member isfilled between the wavelength converting member and the at least oneinner lateral wall part.
 11. The light emitting device according toclaim 1 further comprising a surrounding member disposed on a lowersurface of the wavelength converting member and surrounding alight-incident region of the lower surface of the wavelength convertingmember in which the laser light from the one or more semiconductor laserelement is irradiated.
 12. The light emitting device according to claim11, wherein the wavelength converting member includes a fluorescentmaterial containing part disposed in the optical path of the laser lightemitted from the one or more semiconductor laser elements, and thesurrounding member includes a metal film that surrounds the wiringdisposed on the fluorescent material containing part at the lightincidence surface-side of the wavelength converting member.
 13. Thelight emitting device according to claim 11, wherein the wavelengthconverting member includes a fluorescent material containing partdisposed in the optical path of the laser light emitted from the one ormore semiconductor laser elements, and the surrounding member includesan additional electrically conductive layer disposed on the uppersurface of the light-transmissive cover and surrounding the wiringdisposed on the fluorescent material containing part.
 14. The lightemitting device according to claim 1, wherein the wavelength convertingmember has an uppermost surface located higher than an uppermost surfaceof the package body.
 15. The light emitting device according to claim 1,wherein the light-transmissive cover is made of sapphire.
 16. The lightemitting device according to claim 1, wherein the wiring is disposedcontinuously between two opposite ends of the wavelength convertingmember.
 17. The light emitting device according to claim 1, furthercomprising an insulating layer covering the wiring on the lightincidence surface-side of the wavelength converting member, theinsulating layer defining through-openings through which parts of thewiring are exposed, and a metal film electrically connected to the partsof the wiring through the through-openings and electrically connected tothe electrically conductive layer.
 18. The light emitting deviceaccording to claim 1, wherein the light-transmissive cover is secured ona protruding surface defining a part of a recess formed in the packagebody.
 19. The light emitting device according to claim 18, wherein theprotruding surface is a part of a first step located below an innerlateral wall part which is spaced apart from and surrounds thewavelength converting member.
 20. The light emitting device according toclaim 1, wherein the package body is spaced apart from thelight-transmissive cover, and the electrically insulating member isfilled between the light-transmissive cover and the package body.